发现安卓里一个牛逼的开发工具ViewDebug.ExportedProperty

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使用@ViewDebug.ExportedProperty注解，我们可以在android提供的工具Monitor(或已经废弃的DDMS)中的Hierarchy Viewer中调试View的属性。我们可以直接观察View的某个变量或方法的值，实时观察View的状态变化。

#ExprotedProperty注解源码

/** * This annotation can be used to mark fields and methods to be dumped by * the view server. Only non-void methods with no arguments can be annotated * by this annotation. */@Target({ ElementType.FIELD, ElementType.METHOD })@Retention(RetentionPolicy.RUNTIME)public @interface ExportedProperty {    /**     * When resolveId is true, and if the annotated field/method return value     * is an int, the value is converted to an Android's resource name.     *     * @return true if the property's value must be transformed into an Android     *         resource name, false otherwise     */    boolean resolveId() default false;    /**     * A mapping can be defined to map int values to specific strings. For     * instance, View.getVisibility() returns 0, 4 or 8. However, these values     * actually mean VISIBLE, INVISIBLE and GONE. A mapping can be used to see     * these human readable values:     *     * <pre>     * @ViewDebug.ExportedProperty(mapping = {     *     @ViewDebug.IntToString(from = 0, to = "VISIBLE"),     *     @ViewDebug.IntToString(from = 4, to = "INVISIBLE"),     *     @ViewDebug.IntToString(from = 8, to = "GONE")     * })     * public int getVisibility() { ...     * <pre>     *     * @return An array of int to String mappings     *     * @see android.view.ViewDebug.IntToString     */    IntToString[] mapping() default { };    /**     * A mapping can be defined to map array indices to specific strings.     * A mapping can be used to see human readable values for the indices     * of an array:     *     * <pre>     * @ViewDebug.ExportedProperty(indexMapping = {     *     @ViewDebug.IntToString(from = 0, to = "INVALID"),     *     @ViewDebug.IntToString(from = 1, to = "FIRST"),     *     @ViewDebug.IntToString(from = 2, to = "SECOND")     * })     * private int[] mElements;     * <pre>     *     * @return An array of int to String mappings     *     * @see android.view.ViewDebug.IntToString     * @see #mapping()     */    IntToString[] indexMapping() default { };    /**     * A flags mapping can be defined to map flags encoded in an integer to     * specific strings. A mapping can be used to see human readable values     * for the flags of an integer:     *     * <pre>     * @ViewDebug.ExportedProperty(flagMapping = {     *     @ViewDebug.FlagToString(mask = ENABLED_MASK, equals = ENABLED, name = "ENABLED"),     *     @ViewDebug.FlagToString(mask = ENABLED_MASK, equals = DISABLED, name = "DISABLED"),     * })     * private int mFlags;     * <pre>     *     * A specified String is output when the following is true:     *     * @return An array of int to String mappings     */    FlagToString[] flagMapping() default { };    /**     * When deep export is turned on, this property is not dumped. Instead, the     * properties contained in this property are dumped. Each child property     * is prefixed with the name of this property.     *     * @return true if the properties of this property should be dumped     *     * @see #prefix()     */    boolean deepExport() default false;    /**     * The prefix to use on child properties when deep export is enabled     *     * @return a prefix as a String     *     * @see #deepExport()     */    String prefix() default "";    /**     * Specifies the category the property falls into, such as measurement,     * layout, drawing, etc.     *     * @return the category as String     */    String category() default "";}

#使用

下面是@ViewDebug.ExportedProperty注解的部分属性的使用介绍：

##1.category

category用来指定属性的类别，例如measurement, layout, drawing等。我们在自定义View中为使用@ViewDebug.ExportedProperty注解的变量或方法指定category：

@ExportedProperty(category = "marquee")int x = 1;@Override@ExportedProperty(category = "marquee")public boolean isFocused() {    return true;}

运行程序，在Hierarchy Viewer中查看View的属性如下：

##2.resolveId

当resolveId为true时，如果使用注解的变量或方法的值为int数据，那么这个值会被转化为对应的Android资源的名称。

在R.java中找到一个资源ID：

public static final int activity_main=0x7f030000;

使用注解属性resolveId：

@ExportedProperty(category = "marquee", resolveId = true)int b = 0x7f030000;

结果如下：

##3.mapping

mapping可以将int值映射到指定的字符串值，例如View.getVisibility()返回的值是int值，View中使用注解将其映射为字符串，其中0为”VISIBLE”，4为”INVISIBLE”，8为”GONE”。我们重载View.getVisibility()并加上我们自己定制的映射：

@Override@ViewDebug.ExportedProperty(category = "marquee",        mapping = {                @ViewDebug.IntToString(from = VISIBLE, to = "MARQUEE_VISIBLE"),                @ViewDebug.IntToString(from = INVISIBLE, to = "MARQUEE_INVISIBLE"),                @ViewDebug.IntToString(from = GONE, to = "MARQUEE_GONE")        })public int getVisibility() {    return super.getVisibility();}

结果如下：

##4.indexMapping

indexMapping可以将数组的序号映射为字符串。

@ExportedProperty(category = "marquee",        indexMapping = {                @ViewDebug.IntToString(from = 0, to = "MARQUEE_FIRST"),                @ViewDebug.IntToString(from = 1, to = "MARQUEE_SECOND"),                @ViewDebug.IntToString(from = 2, to = "MARQUEE_THIRD")        })int[] elements = new int[] {        111, 222, 333};

结果如下：

#Demo

package com.daemon.demo;import android.content.Context;import android.graphics.Rect;import android.util.AttributeSet;import android.view.ViewDebug;import android.view.ViewDebug.ExportedProperty;import android.widget.TextView;public class MarqueeText extends TextView {    public MarqueeText(Context context) {        super(context);    }    public MarqueeText(Context context, AttributeSet attrs) {        super(context, attrs);    }    public MarqueeText(Context context, AttributeSet attrs, int defStyle) {        super(context, attrs, defStyle);    }    @Override    protected void onFocusChanged(boolean focused, int direction, Rect previouslyFocusedRect) {    }    @ExportedProperty(category = "marquee")    int x = 1;    @Override    @ExportedProperty(category = "marquee")    public boolean isFocused() {        return true;    }    @ExportedProperty(category = "marquee", resolveId = true)    int b = 0x7f030000;    @Override    @ViewDebug.ExportedProperty(category = "marquee",            mapping = {                    @ViewDebug.IntToString(from = VISIBLE, to = "MARQUEE_VISIBLE"),                    @ViewDebug.IntToString(from = INVISIBLE, to = "MARQUEE_INVISIBLE"),                    @ViewDebug.IntToString(from = GONE, to = "MARQUEE_GONE")            })    public int getVisibility() {        return super.getVisibility();    }    @ExportedProperty(category = "marquee",            indexMapping = {                    @ViewDebug.IntToString(from = 0, to = "MARQUEE_FIRST"),                    @ViewDebug.IntToString(from = 1, to = "MARQUEE_SECOND"),                    @ViewDebug.IntToString(from = 2, to = "MARQUEE_THIRD")            })    int[] elements = new int[] {            111, 222, 333    };}

#参考

@ViewDebug.ExportedProperty

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